Repairs


making a ducted blower from a computer fan

making a ducted blower from a computer fan
DIY in line ducted fan
I need a battery box vent for my solar batteries enclosure. Many people sell fans that can be installed in PVC piping, but they are expensive.
I have a bunch assorted fans from 2" to 4" from the MIT swap meet, so I set out to make a ducted fan assembly for them.
I found that the white PVC reducers were just the right size, so I took some white expanded PVC foam board, and using a 4" hole saw bade a simple flange. I glued the flange to the reducer, and used some long 6-32 screws and now have a nice ducted fan that can be inserted into the 1.5" PVC vent line. Made another for a 2.5" fan.

Broken gas can cap

Broken gas can cap
Fixing a broken gas cap
New England weather can get nasty, so having a generator and some gas is almost a necessity.
I bought several 6 gal cans a few years ago, and one of the plastic caps split, and would not seal.
I went on a quest to buy a replacement cap, but as was my experience in the past, they seem to keep changing the threads and size, and none of the replacements would work.
I bought a new gas can last time, but hate to trash a perfectly good gas can for lack of a working cover.
I washed the broken gas cap in alcohol to get any residue off. Then cut some small strips of my favorite aluminum tape, and carefully taped the cracked cover back in the correct shape.
The type of plastic they use does not glue well, and there is a lot of stress on the cap when tight, so I got out my trusty epoxy putty, and mixed up enough to totally cover the cap.
I rough sanded the plastic cap, and made some light saw cuts to give the epoxy something to attach to,
and I made sure to get some under the bottom lip of the cap, so the broken cap was totally encased in the putty. The epoxy cured overnight, and the cap now works just like new, and I expect that this cap may last longer than the virgin ones.

Lifting the battery safely

Lifting the battery safely
Some insight battery pack lifting options
As anyone that has pulled the battery pack on their insight can tell you, it is just heavy enough to hurt your back, and it requires you to lift in a very awkward position. Honda has a special lifting frame that the techs use, so I thought that with the requirement that one pulls the Insight pack to do a clean grid charger install,it was time to see if a quick and dirty version of the lifting frame could be fabricated.
Randall sent me a photo of one he made, using some handles, and a piece of plywood.

I made one with long handles, that allow comfortable lifting angles, and full control of the pack while removing or installing.

Insight Oil Pan second chance

Insight Oil Pan second chance
Oil Pan second chance
Thanks to Jim Alger at Find My Insight who sent me a stripped out oil pan, I believe I have a better solution to the expensive replacement that many people have faced.
This may have actually been part of the design, as I cannot see any other reason they would have put that strange O-ring retainer in the stack of washers.
I carefully looked at the pan, and saw that there were at least 4 complete threads in the rear of the stripped out magnesium hole. I quickly realized that if the crush washer, and O-ring plate were gone, and I cleaned the remains of the old threads out of the hex bolt, that it threaded in fully, and actually came out the other side with the full 4 threads to hold on to.
I got out the trusty gasket punch set, and made a nice 1/8" thick rubberized cork washer.
I screwed the bolt back in, and found that from first resistance(initial crush), to where I felt I was going to squeeze out the cork (not likely)that I had nearly a 1/4 turn. This should seal easily between the hex plugs polished underside, and the nice flat surface of the oil pan. The only question that remained was could it work loose over repeated hot cold cycles.
I decided that since there was already a nice blind threaded hole and bolt left over from the O-Ring washer, that I may as well make a hex plug anti rotation retainer,
I dug up a thin aluminum sheetmetal plate, and drilled a hole that was just a smidge larger than the distance across the hex head flats of the hardened plug. This hex is 17MM, so as a backing cavity I used a 6 point socket, and pressed the hex head through the aluminum with my drill press. This cold forms the aluminum to make a nice snug fitting hex hole to fit the hex head of the plug. I cut out the aluminum and made a narrow tab, then carefully bent the tab to slightly less than the wide base of the hex plug and the cork washer so it would not bottom out when applied.
Finally I drilled a clearance hole in the tab for the retaining screw.
I tightened the plug with the retainer in position till the hole lined up, put in the screw, and believe that this oil pan will work as good as it did before stripping out, all without the need to do any machining or removal of the oilpan, and with only the addition of a single sealing washer.
Cork rubber is good in oil, and is rated for -40F to 180F. I just happened to have a piece, but a better washer material may be Aramid/Buna-N, which is rated for -40 to 700F
You can buy a pack of 5- 5/8" X 1" X .062 Aramid/Buna-N
washers from http://www.mcmaster.com/
Part # 93303A284 for $8.10

aluminum tape again

aluminum tape again
Re-Sealing that can
I needed to varnish a piece of wood, and as usual, the cover of the can was stuck so strongly (had been previously opened) that I had to damage the seal to get the cover off. Faced with loosing the rest of the mostly full gallon of varnish, I pulled out the roll of aluminum tape again, and was able to seal the top.
Results:
I opened the can three weeks after sealing it, and the varnish was perfect, with no skin on the surface.Looks like it works.

How I splice audio cables

How I splice audio cables
Splicing delicate shielded wires
I got some nice amplified speakers the other day, and expected to plug them into the two audio out jacks on the back of my TV.I take it out of the box and find that it has a cable with a 1/8 " stereo plug, not the RCA plugs that my TV has.The speakers were designed for PC audio or gaming.
I dig into my huge cable case and find a nice dual color coded RCA audio cable that was cut off to make an audio input cable for a device I built.Never throw away anything, so heres the proof that you should save everything that can be used again.
Audio cables are a difficult splice because the wires are so delicate. This splice is stronger than the wires on either end, fully insulates and encapsulates and waterproofs the splice, and is tough as nails. works for other splices as well.

Fixing small plastic gears

Fixing small plastic gears
Armatron disassembled
I pulled out my old favorite toy, the Armatron, to show a young friend. It did not work. The gripper would not work. I set out to fix it.
After taking it apart the wrong way,by trying to disassemble the arm a section at a time, I soon figured out the right way, first remove the whole arm from the shoulder. The arm has two screws holding the square Armatron cover to the main shoulder area. Once that is removed, the two screws with big washers at the main shoulder joint are to be removed next. Then gently bend out the thin plate from the right side of the arm(side with no gear rack). This will allow you to totally disconnect the arm from the body. The arm sections are easily disassembled by removing the screws and covers. Don't forget where each shaft goes, and watch out that the shafts don't all fall out when you remove the covers.Some of the shafts are used in a not intuitive way.
This is probably the most mechanically complex toy ever made,and is a really chalenging take it apart/put it back together puzzle.
The base and control joysticks all are driven by a single motor. each axis of the joystick has two speeds and a neutral.
If there is an interest, I can expand this armatron examination, and get into the whole drive train, as the gear shifting and power take off is really interesting.
The problem was discovered,I found that a 10 tooth gear had split, and the gear was spinning on the shaft. I took a brass rod and drilled then bored a hole in it that was .001" smaller than the gear OD. Then I turned the brass rod OD so I had a thin brass tube. I tapered the inlet side, then pressed it over the broken gear. Then I pressed the gear back onto the shaft. The gear is still split, but will not slip on the shaft and the grippers now work properly.
An old friend with a home built CNC machine made me a replacement. Thanks Bill, my toy is fixed.

Black tape and PVC cement

Black tape and PVC cement
Making it one piece
I have been using black electrical tape since I was a kid.
My Dad was a DIY of considerable skill, and I used to play in the basement and be his helper, he always had several rolls of tape so it became one of my toys.
Black tape has many uses, and has certain properties that make it a versatile tool.
Insulation:
The main use of black electrical tape is to cover bare electrical wires. If applied correctly, the tape will last for many years. If applied incorrectly, it will start to separate and get sticky in short order. Each wrap is good for 200-600V depending on the thickness, so a carefully taped wire can have better insulation than the wires on either side.
The tape is designed to be pliable and stretch so it can conform to irregular surfaces. The trick to making a tight long lasting covering with tape is in when and how much you stretch it.
Temperature extremes will make black tape stretch and contract, loosening the adhesion in the layers. To prevent this, when making the final wrap, always do it with nearly zero tension in the tape, to prevent the end from shrinking back when heated. A final and powerful way to make the taped joint stay together, is to use PVC pipe cement to coat the outer layer of tape and glue it together. The cement sets up in a few minutes, and will protect the tape for many years even outdoors in the weather, and the joint is waterproof.

The inner wraps need to be fairly tight so air is not trapped in side.
The quality of black tape is a measure of how much stretch can be put into the tape before it breaks. Never stretch to more than 70% of the breaking point, as breaking point and pliability drop when the tape joint gets cold, and the tape could crack through all layers.